The paper examined the vegetation coverage dynamic and its response to climate elements in Yellow River Basin from 1998 to 2008 by an integrated approach made from series methods including correlation analysis, wavelet analysis, and wavelet regression analysis. The main findings are as follows: (1) Vegetation coverage exhibited significant, positive correlation with temperature and precipitation, but negative correlation with sunshine hours and relative humidity at some sites. The correlation between NDVI and precipitation is closest, followed respectively by temperature, relative humidity, and sunshine hours. Precipitation and temperature are the two major climate elements affecting vegetation coverage dynamics. (2) The vegetation coverage dynamics reflected by NDVI time series presented nonlinear variations that depended on the time-scale. Precipitation and temperature both presented nonlinear variations that were morphologically similar with those of NDVI. These further supported the close relationship between NDVI and these two climate elements from a new perspective. (3) Although NDVI, temperature, and precipitation revealed nonlinear variations at different time scales, the vegetation coverage showed a significantly, positively linear correlation with temperature and precipitation at all the time scales under examination.
Jianhua Xu is an Academic Editor for PeerJ.